Second North American Sea Duck Conference - Patuxent Wildlife ...

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SECOND NORTH AMERICAN SEA DUCK CONFERENCE ARE FEMALE COMMON EIDERS (SOMATERIA MOLLISSIMA) CAPITAL OR INCOME LAYERS? Yves Rigou and Magella Guillemette Département de biologie, Université du Québec à Rimouski, 300 allée des Ursulines, Rimouski, Québec G5L 3A1, Canada; yves.rigou@uqar.qc.ca One nesting phase that is particularly costly for waterfowl species is the production of the clutch. The female needs to gather a large amount of food in order to transfer nutrients (from endogenous reserves or directly from the food) to the growing follicles. In this paper, we test the idea that (1) female common eiders transfer nutrients directly from food ingested to ovary growth during prelaying and, (2) females feed during laying. Using published information from three studies, (1) body condition of pre-laying females was assessed in relation to follicular growth, (2) body mass of females and, (3) nest attendance pattern while laying are reported. Somatic body mass and body composition of birds collected around a nesting colony, in the Baltic sea, did not change significantly in relation to three categories of ovary growth. Sixty-four percent of the females studied lost body mass, twenty-seven percent had a constant mass and nine percent gained mass while laying resulting in an average decrease of body mass of 39 g (SD ± 63), which is less than the average mass of a fresh laid egg. Attendance patterns showed that females left the nest for most of the night and a part of the day during the first days of the laying phase and that time spent off the nest decreased steadily from the first to the last egg laid in the clutch. Altogether, these results suggest that (a) the clutch produced by female common eiders nesting in the Baltic is composed of nutrients derived mainly from food collected around the breeding colony, (b) females continue to feed during laying which is consistent with the fact that (c) ample time is spent off the nest during the laying phase. 108 ANNAPOLIS, MARYLAND, USA NOV. 7-11, 2005
SECOND NORTH AMERICAN SEA DUCK CONFERENCE EFFECTS OF BACKPACK RADIO-TRANSMITTERS ON FEMALE BARROW’S GOLDENEYES Michel Robert, Bruno Drolet, and Jean-Pierre L. Savard Canadian <strong>Wildlife</strong> Service, Quebec Region; michel.robert@ec.gc.ca Based apparently on a single study on canvasbacks (Aythya valisineria), diving ducks have long been considered especially sensitive to transmitters attached with backpack harnesses. As part of a larger study, we compared time-budgets and return rates of breeding female Barrow’s goldeneyes (Bucephala islandica) fitted, or not, with transmitters attached with backpack harnesses in 2001- 2004 in southern Québec. We compared the mean proportion of time devoted to feeding, locomotion, alert, resting, preening, and maintenance i.e., resting plus preening. Brooding females (i.e., females with ducklings) with backpacks spent significantly less time feeding [25% ± 5 (SE) versus 43% ± 3] and more time in maintenance activities (51% ± 6 versus 31% ± 4) than brooding females without transmitters. Mean time devoted to other behaviors did not differ significantly. Upon release, females appeared preoccupied with the backpack and behaved in a similar way, actively bathing, preening, and/or beating wings. Of the females with transmitters observed more than 200 minutes (N = 5), three spent 4%, 8%, and 57% of their preening time at their transmitter, antennae or harness. None of the 16 females harnessed in 2001-2003 were recaptured in nest boxes or seen again on the study area in 2002-2004. For comparison, 66% of adult female Barrow’s goldeneyes captured in nest boxes and marked with leg bands in 2000-2002 were recaptured or seen again in subsequent years, a significant difference. If Barrow’s goldeneye females marked with nasal disks are included, the return rate is 43% and still significantly different. We do not know why none of the harnessed Barrow’s goldeneyes returned to our study area, although we consider severe winter conditions and icing are probably a cause. As a result, we do not recommend the use of harnesses on diving and seaducks as it may affect their behavior and survival, at least for birds wintering in areas where conditions are particularly severe, as Barrow’s goldeneyes from eastern <strong>North</strong> America. NOV. 7-11, 2005 ANNAPOLIS, MARYLAND, USA 109
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